CORN BREEDING 



139 



each square bearing a number corresponding to the number on one 

 of the ears. Six or ten grains taken from different parts of each 

 ear are placed on the square bearing the same number as the ear. 

 Another cloth (or cloth bag containing damp sawdust) is laid over 

 the squares containing the grains to be tested, and over this second 



Fig. 73. — Gbrminatob made from a Soap Box, and heady to 



KECEIVB THE SeED. 



cloth is spread about an inch of moist sand or damp sawdust. 

 The box is placed in a warm room, and in seven to ten days 

 a count is made to determine which ears sprout properly. Do not 

 use for planting any ear which bore a grain that failed to sprout. 



126. Crossing versus selection. — Crossing two dis- 

 tinct varieties results in variation (or a lack of uniformity) 

 in the plants; uniformity may not again be completely 

 established even after five or ten years of subsequent 

 selection. Hence it is usually better for the "farmer to 

 improve his corn by selections among the individual plants 

 of a single variety than to attempt to cross two dissimilar 

 varieties. 



However, since crossing in certain rare cases is advisable, 

 and since it often takes place accidentally, a few of the 

 simpler effects of crossing are briefly discussed. 



127. Definitions of degrees of relationship between 

 corn plants. — Self-poUination or in-breeding consists in 

 placing the pollen of one plant on the pistil (silks) of the 



